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Ravindra, Nuggehalli M.; Sopori, Bhushan; Gokce, O. H.; Cheng, Shu Xia; Shenoy, A.; Jin, Li; Abedrabbo, Sufian; Chen, W.; Zhang, Y.

doi:10.1023/a:1012869710173

Cited by 101 publications

(23 citation statements)

References 7 publications

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“…As the signal measured on the lock-in amplifier again corresponds to the difference between the thermal emission when the current is on and off, the calculated spectra were obtained by calculating the difference between two grey-body curves, one corresponding to emission from the hot graphene when the current is on, and the second corresponding to the cooler background temperature of the underlying silicon dioxide/silicon when the current is off, consistent with the mapping measurements. Values of 2%, 6% and 6% were taken for the emissivity of the monolayer, multi-layer, and silicon respectively, 21 yielding temperatures of the graphene and background silicon chip of 600 K and 350 K for the monolayer, and 620 K and 480 K for the multilayer devices (as the currents are applied for many hours during measurements, the silicon substrate reaches an equilibrium background temperature). Note that we are assuming that the graphene emitting area reaches equilibrium with the underlying substrate when the current is off, but further work would be needed to confirm this.…”

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confidence: 99%

Prospective for graphene based thermal mid-infrared light emitting devices

et al. 2014

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We have investigated the spatial and spectral characteristics of mid-infrared thermal emission from large area Chemical Vapor Deposition (CVD) graphene, transferred onto SiO2/Si, and show that the emission is broadly that of a grey-body emitter, with emissivity values of approximately 2% and 6% for mono- and multilayer graphene. For the currents used, which could be sustained for over one hundred hours, the emission peaked at a wavelength of around 4 μm and covered the characteristic absorption of many important gases. A measurable modulation of thermal emission was obtained even when the drive current was modulated at frequencies up to 100 kHz.

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confidence: 99%

Prospective for graphene based thermal mid-infrared light emitting devices

et al. 2014

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“…When a material is semitransparent, the emittance can increase drastically due to the large chance of light trapping by total internal reflections inside the material. Some previous studies calculated the emittance of rough silicon wafers by considering surface roughness as a parameter in an emittance model without considering the actual statistics of the surface topography [3,4]. In the present study, we calculate the emittance from the BRDF obtained from a Monte Carlo ray-tracing method, which incorporates the actual surface statistics to investigate the effect of anisotropic roughness on the directional spectral emittance.…”

Section: Monte Carlo Modelingmentioning

confidence: 99%

“…Many researchers have studied the emittance of rough silicon surfaces for accurate radiometric temperature measurements during rapid thermal processing [3][4][5]. Vandenabeele and Maex [3] measured the emittance of wafers with varying degrees of surface roughness and found that even moderate roughness can enhance the emittance for wafers in the semitransparent spectral region.…”

Section: Introductionmentioning

confidence: 99%

Measurement and Modeling of the Emittance of Silicon Wafers with Anisotropic Roughness

2007

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The unpolished surface of crystalline silicon wafers often exhibits nonGaussian and anisotropic roughness characteristics, as evidenced by the side peaks in the slope distribution. This work investigates the effect of anisotropy on the emittance. The directional-hemispherical reflectance of slightly and strongly anisotropic silicon wafers was measured at room temperature using a center-mount integrating sphere. A monochromator with a lamp was used for near-normal incidence in the wavelength region from 400-1000 nm, and a continuous-wave diode laser at the wavelength of 635 nm was used for measurements at zenith angles up to 60 • . The directional emittance was deduced from the measured reflectance based on Kirchhoff's law. The geometricoptics-based Monte Carlo model that incorporates the measured surface topography is in good agreement with the experiment. Both the experimental and modeling results suggest that anisotropic roughness increases multiple scattering, thereby enhancing the emittance. On the other hand, if the wafer with strongly anisotropic roughness were modeled as a Gaussian surface with the same roughness parameters, the predicted emittance near the normal direction would be lower by approximately 0.05, or up to 10% at a wavelength of 400 nm. Comparisons also suggest that the Gaussian surface assumption is questionable in calculating the emittance at large emission angles with s polarization, even for the slightly anisotropic wafer. This work demonstrates that anisotropy plays a significant role in the emittance enhancement of rough surfaces. Hence, it is imperative to obtain precise surface microstructure information in order to accurately predict the emittance, a critical parameter for non-contact temperature measurements and radiative transfer analysis. 9180195-928X/07/0600-0918/0

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“…Emissivity, ε, is determined from the expression ε ϭ 1 Ϫ R Ϫ T, where R and T are the measured reflectivity and transmissivity, respectively. 32 By optical reciprocity, the absorptivity is determined by the emissivity. The surface texture in the single-side polished wafer (10-30 µm laterally, 1-µm rms vertically) is seen to increase the emissivity.…”

Section: Optical Confinementmentioning

confidence: 99%

“…The spectral emissivities of the rough and smooth sides of a single-side polished Si wafer and of a double-side polished Si wafer 32. …”

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Light emission from silicon: Some perspectives and applications

Fiory

Ravindra

2003

Journal of Elec Materi

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Research on efficient light emission from silicon devices is moving toward leading-edge advances in components for nano-optoelectronics and related areas. A silicon laser is being eagerly sought and may be at hand soon. A key advantage is in the use of silicon-based materials and processing, thereby using high yield and low-cost fabrication techniques. Anticipated applications include an optical emitter for integrated optical circuits, logic, memory, and interconnects; electro-optic isolators; massively parallel optical interconnects and cross connects for integrated circuit chips; lightwave components; highpower discrete and array emitters; and optoelectronic nanocell arrays for detecting biological and chemical agents. The new technical approaches resolve a basic issue with native interband electro-optical emission from bulk Si, which competes with nonradiative phonon-and defect-mediated pathways for electron-hole recombination. Some of the new ways to enhance optical emission efficiency in Si diode devices rely on carrier confinement, including defect and strain engineering in the bulk material. Others use Si nanocrystallites, nanowires, and alloying with Ge and crystal strain methods to achieve the carrier confinement required to boost radiative recombination efficiency. Another approach draws on the considerable progress that has been made in high-efficiency, solar-cell design and uses the reciprocity between photo-and light-emitting diodes. Important advances are also being made with siliconoxide materials containing optically active rare-earth impurities.

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Cited by 101 publications

References 7 publications

Prospective for graphene based thermal mid-infrared light emitting devices

Prospective for graphene based thermal mid-infrared light emitting devices

Measurement and Modeling of the Emittance of Silicon Wafers with Anisotropic Roughness

Light emission from silicon: Some perspectives and applications

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